The influence of unsaturation modifications on the tribological characteristics of bio-based lubricants obtained from vegetable oils: a review
摘要
The current need for energy transition has driven research on the production of new fuels and lubricants from more biodegradable and renewable raw materials. In this context, the chemical synthesis of vegetable oils and animal fats—from which esterification/transesterification, epoxidation, oxirane ring opening, hydrogenation, and estolide formation stand out—is being successfully applied in generating biolubricants with physicochemical characteristics comparable to those of commercial mineral lubricants. In this article, a literature review was conducted to identify and present outlines of the formation of the lubrication mechanisms of the molecules obtained via the aforementioned chemical processes when subjected to tribological tests. Collected data suggest that biolubricants formed by the association of polar groups and with a lower unsaturation content are more efficient at forming lubricating films that reduce friction and resist wear-inducing shear forces. These chemical pathways demonstrate the possibility of obtaining lubricants with numerous characteristics that depend both on the base oil used and the reagents involved, showing that the future of biolubricants lies in improving these methods.